[BUG] [JAVA] [Restclient] ApiClient incompatible with Spring Framework 7 HttpHeaders

[typat]

Description

Spring Framework 7 removed several methods from the HttpHeaders class. The generated ApiClient template uses removed methods (containsKey and entrySet) that have been removed in favor of new methods (containsHeader and headerSet).

spring-projects/spring-framework#33913

https://github.com/spring-projects/spring-framework/wiki/Spring-Framework-7.0-Release-Notes#httpheaders-changes

openapi-generator version

7.14.0

OpenAPI declaration file content or url

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache#L362

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache#L715

Generation Details

Spring Framework 7.0.0-M7 or Spring Boot 4.0.0-M1

generatorName = "java"
library = "restclient"

Suggest a fix

headerSet() exists as of Spring Framework 6.1.15 but containsHeader was added with Spring Framework 7.0, and unfortunately at this time there is no fallback or intermediate solution, and likely a new generation option for using Spring Framework 7 or Spring Boot 4 might be necessary.

[typat]

I'm happy to open a PR, but some direction would be nice. Obviously we can't just update the usage of these methods, but I might open an issue with Spring Framework to add these methods back in a deprecated state to allow for an easier migration.

[phactum-mnestler]

Ran into the same issue when trying out Spring Boot 4 compatibility. The containsHeader issue can likely be resolved by using HttpHeaders.set instead of containsKey+remove + add, which would likely be clearer anyway:

    public ApiClient addDefaultHeader(String name, String value) {
        defaultHeaders.set(name, value);
        return this;
    }

[wing328]

@phactum-mnestler do you mind opening a PR with the suggested fix?

these are the related lines in the mustache files provided by @typat

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache#L362

https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache#L715

@typat can you please review the suggested fix to see if that works for you too?

[ahoehma]

Beside how to fix this spring migration in the generator (template) it should be possible to configure the "spring-version" to use. Because if this fix change to springboot 4+ .. .then all 3.5.x project will fail.

[wqrts]

Beside how to fix this spring migration in the generator (template) it should be possible to configure the "spring-version" to use. Because if this fix change to springboot 4+ .. .then all 3.5.x project will fail.

Could use if (headers.get(headerName) != null) in the code base as that will be portable between both SF 6 and SF 7?

[legion47T]

The same problem exists with Spring WebClient. I was hestitant to open an almost identical issue for it but can do that of course, if you think it might be better to seperate the two.

I had a look at what might need to be changed for WebClient. It currently depends on Spring Boot Starter WebFlux version 3.0.12. This would need to be raised to 3.2.12 to depend on Spring Framework version 6.1.15.
Afterwards the same fix as in #21691 should be applicable.
Should I draft such a PR?

[wing328]

Thanks for the PR from @legion47T which has been merged.

Please pull the latest master to give it a try and let us know if you've any question/feedback

[ahoehma]

Late feedback ... this change works pretty well for me! Thanks.